Versium

Versium is a simple abstract API over several storage solutions, all of
which provide access to a collection of versioned documents or "nodes".
Nodes carry Lua byte-string data as their payload, but no assumptions
are made about its content. The client interacts with versium through
the "versium" module, which then delegates most of the work to a
specific storage implementation (specified at the initialization time).
Two storage implementations are included with this rock: "simple" which
stores nodes and their histories on the file system and "virtual" which
stores them in memory. Other implementations (e.g., using subversion or
a database) are provided as separate rocks.